Turntable drydock



July 25, 1967 A. BURNETT 3,332,248

TURNTABLE DRYDOCK Filed Jan. 29, 1964 4 Sheets-Sheet 1 INVENTOR n ARDEN L. BURNETT July 25, 1967 A. L. BURNETT 3,332,248

TURNTABLE DRYDOCK Filed Jan. 29, 1964 4 Sheets-Sheet 2 INVENTOR ARDEN L. BURNETT FIG. 3.

BY Ma).

I ATTYS.

July 25, 1967 A. 1.. BURNETT 3,332,248

TURNTABLE DRYDOCK Filed Jan. 29, 1964 4 Sheets-Sheet 3 o-Jauu ouquamauuuwmquuonmauaulud 37 25 2 OOUOOOOOOOOOOOOOOOO l 49 57 5| PUMP CONTROL 2' 11' III I r 1 IL 11111 I; 1 IIIT f 53 AIR TANK w L "-'"j 45 l j Ea f: T 55 E T rm INVEN 0 4? 47 T R ARDEN L. BURNETT FIG. 6.

ATTYS.

United States Patent 3,332,248 TURNTABLE DRYDOCK Arden L. Burnett, 619 Nicholson Ave., Falls Church, Va. 22044 Filed Jan. 29, 1964, Ser. No. 341,149 Claims. (Cl. 61-64) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to the drydocking of ships and more particularly to a drydocking and undocking system capable of handling several ships or other large equipments at the same time.

The use of drydocks for ship repairs is an old art but still a necessary one. Drydocks, however, are very costly and as presently utilized, usually allow repair of only one ship at a time. When two or more ships are in the same floating or graving dock, it is impossible to launch one without floating the others. It was suggested many years ago that it is possible to utilize a drydock basin as a tumtable in the center of a ship repair area wherein the ships can be turned so that they may be moved from the basin or railways to a plurality of repair areas. The use of a turntable has of course, been common practice for many years in railroad yards.

Extreme difficulties would be encountered, however, in attempting to use such a system in a shipyard. Unless a floatable pontoon or drydock were used, difficulty would be encountered in raising large ships high enough to enable their movement on railways. If pontoons or a floating dock were used to raise the ship high enough to allow the ship to be moved from the pontoon to railways, severe buoyancy difficulties would be experienced as the ship is transferred from floating pontoon to the railway due to the changing weight distribution on the pontoon.

The general purpose of the present invention is to provide a turntable drydock system which possesses none of the aforedescribed disadvantages. To attain this, there is provided a turntable arrangement which includes a pontoon dock having a selective ballasting system and an automatic control system therefor. The system is also adaptable to building other larger objects such as rockets. The turntable is referred to herein as a pontoon dock. A pontoon dock is also known in the-art as a floating drydock.

An object of the present invention, therefore, is to provide a system for drydocking ships in large numbers.

Another object is to provide a manufacturing and repair facility for large water-transportable objects such as rockets or the like.

A further object is the provision of a drydocking system which is more economical in cost, labor, and materials than systems presently in use.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like or corresponding parts throughout the figures thereof and wherein:

FIG. 1 is a top view in perspective of an overall embodiment of the invention;

FIG. 2 is a top view of another embodiment of the invention wherein the turntable is allowed to rotate a full 360;

FIG. 3 is a partially diagrammatic cross-sectional view of :the embodiment of FIG. 2 with the basin dewatered and showing a ship on a pontoon dock on the basin floor;

FIG. 4 is a cross-longitudinal view of FIG. 1 (similar to FIG. 3) showing a ship floating on the pontoon dock at yard level;

FIG. 5 is a diagrammatic top view of the pontoon of FIGS. 14;

FIG. 6 is a diagrammatic cross-sectional view of the pontoon dock of FIG. 5, showing details of an embodiment of the electrical portion of a buoyancy control system;

FIG. 7 is a block diagram of an alternate embodiment of the electrical portion of the buoyancy control system shown in FIG. 6;

FIG. 8 is a diagram of an alternate embodiment of the sensing means for use in the buoyancy control system shown in FIG. 6; and

FIG. 9 is a diagrammatic view partly in cross-section illustrating the functioning of the buoyancy control system.

Referring now to the drawings, there is shown in FIG. 1, which illustrates an overall perspective view of an embodiment of the invention, a drydock basin 11 which has an entrance from a surrounding body of water and which may be sealed by means of a floatable caisson 13 selectively positionable in a double faced caisson seat 15 formed in the walls and floor of the entrance to the basin area 11. The caisson 13 and seat 15 are provided with means for seating the caisson and means for sealing water either into or out of the basin area as described in my copending Patents 3,133,420 and 3,133,518, Ser. No. 20,504, filed Apr. 6, 1960. This provision allows adjustment of the water level within the basin relative to the water level outside and also insures that docking is not dependent on or interfered with by the level of the tide. It will be understood by those skilled in the art that instead of a double faced caisson seat, separate seats may be used, if desired, for sealing water within the basin and for sealing the basin against water outside the basin; the caisson being moved from one seat to the other as needed. The caisson may be positioned to keep water out of the basin, or to keep water in the basin at a higher level than the outside water, 'or to prevent tidal water from interfering with docking operations. The basin 11 as ilustrated in FIG. 1 may be of any suitable shape, for example, in the shape of a segment of a circle at the top level and in the bottom portion rectangular in the shape of a standard graving dock. Where there is negligible tide or where the caisson is not needed to raise water in the basin, the general shape of the facility may approximate that of a segment of a circle if one or two land-side railways are provided.

Located within the basin 11 is a pontoon dock or floating dock 17 which may be equipped with rails 19 for movably supporting a ship thereon. As will be described hereinafter, the pontoon dock 17 is provided with buoyancy control means so that the pontoon dock may be sunk to the bottom of basin 11 while the basin is filled with water whereby a ship may be floated into the basin over the floor of the pontoon dock. By forcing water from the pontoon, the pontoon can be raised to lift the ship out of the water. A floating dock may also serve as pontoon 17.

As further shown in FIG. 1 the basin 11 must be sufficiently deep in one portion 21 to allow the ship to be floated over the sunken pontoon dock 17. The remainder 23 of the basin may be of shallower depth, thereby saving excavation costs in building the facility. The remaining portion 23 needs only sufiicient depth to accommodate the pontoon dock 17 when the same is floating with its rails 19 approximately at yard level. The yard is provided with a plurality of railways 25 which each run from the 3 edge of the basin 11 to any convenient repair or building area nearby.

A plurality of keys 27 may be provided on the pontoon dock for cooperation with a plurality of keyways 29 in the basin walls for holding the pontoon against transverse movement after it is placed in any given position.

As may be seen from FIG. 2, the basin may, if desired, be completely circular in shape as shown at 11'. In this embodiment of the invention, there is again provided a deep center basin portion 21 and a shallow edge portion 23 at each side of the basin. As also shown in the drawing of this embodiment, there may further be provided a plurality of support pilings in the basin in line with each of the railways 25 whereby the pontoon clock 17 may be partially supported by pilings while a ship 33 is being transferred from the pontoon dock to the selected one of the railroads 25, as will be described in further detail hereinafter.

Referring now to the cross-sectional drawings of FIG. 3, a plurality of pilings 35 may also be provided in the bottom of the deep water portion 21 of the basin 11 for supporting the pontoon dock 17 when the pontoon dock is in its sunken position. The ship 33 is carried on the pontoon dock 17 by means of rail mounted dollies 37 which support the ship hull by means of blocking 39. The dollies 37 and blocking 39 must have a negative buoyancy, i.e. they must be made dense enough to sink when not supported.

In operation, initially the basin 11 is allowed to flood to the level of the surrounding water with the pontoon jack 17 resting on the pilings 35 on the bottom of the deep portion 11 and with dollies 37 and blocking 39 positioned on the rails 19 of the pontoon dock. The caisson 13 is moved out of the basin entrance and the ship to be repaired is floated into the basin over the pontoon floor. The caisson 13 is then positioned in its seat in a position to seal the basin 11 against surrounding water. With the ship in position over the pontoon dock 17, water is pumped from the basin until the ship rests on the blocking 39. Water is then removed from the pontoon dock 17 in an amount sufficient to cause the pontoon dock to float while supporting the ship, water is then allowed to enter the basin and fill it to the level of the water outside the basin. Instead of removing water from the basin the pontoon dock may lift the ship from the water by further deballasting of the pontoon compartments. After the basin has been filled to the level of the Water outside the basin, the caisson 13 is reseated in position to hold water within the basin and water is pumped into the basin in an amount suflicient to float the dollies 37 on the pontoon dock to, or slightly above, yard level. The pontoon dock 17 is then turned to align it with the desired one of the yard railways and the level of the pontoon dock is adjusted by drain ing water from the basin thereby causing the bottom of the pontoon dock to rest on side wall 23, so that the top rail 19 coincides with the level of the yard railings so that the ship may be rolled on its dollies 37 from the pontoon dock to the selected yard railway. If the basin is provided with pilings 31 which may, if desired, be interconnected with beams as shown in FIG. 2, the pontoon dock 17 rests on the pilings as the ship is moved from the pontoon dock to the yard railway. Instead of providing the support pilings 31, it is also possible to provide only sufficient depth in the shallowest part of the basin to allow the pontoon dock to rest lightly on the bottom. While allowing the pontoon dock to rest lightly or hover over some type of bottom support, as its load is being transferred as desirable for stability, it will be realized that it is possible to transfer the ship to a yard railway while the pontoon dock is completely afloat.

As is shown in the drawings, the pontoon dock is of sufficient length to substantially span the basin.

After the pontoon dock with the ship thereon, is raised by raising the water level to or slightly above yard level and the pontoon dock is turned to overlie the shallower side portions 23 or 23 of the basin with its fore and aft portions, the central portion of the pontoon dock spans or overlies the deeper central portion of the basin, while being still supported by the water.

In any case, the system as thus far described would inherently present serious problems. The pontoon dock, when afloat and supporting a ship, must have a high positive buoyancy in order to remain afloat under the weight of a ship. In accordance with methods known in the art this variation of buoyancy is accomplished by making the pontoon dock hollow and either filling the pontoon dock with water or pumping water from the pontoon dock until the buoyancy is equal to that desired. The problem arises in the fact that as the load on the pontoon dock is transferred from the pontoon dock to a dockside location the load on the pontoon dock becomes unevenly distributed. The unloaded part of the pontoon dock begins to rise while the loaded portion remains low in the water. As the unloaded end rises, water in the unloaded end flows toward the loaded end making the unloaded end even more buoyant and the loaded end less buoyant thereby causing an even greater buoyancy differential across the length of the pontoon dock. In aggravated situations the loading at one end could cause the pontoon dock to be ejected from under the dollies and the ship to be dropped into the dock basin.

The problem is accentuated by the fact that a ship materially varies in weight along its length. For example, a ship may weigh ten tons in an end area and may weigh twenty tons in another area. This will cause varying displacement or deflection of the pontoon dock at various points or areas along its length. Consequently, when the ship moves even slightly relative to the pontoon dock in being transferred from the pontoon dock to a dockside location, the entire situation regarding the weight or load distribution on the pontoon dock and the displacement or deflection of the various portions of the pontoon dock is immediately and drastically changed.

A system for obviating the aforementioned problem is shown in FIGS. 58. As shown in FIG. 5, the pontoon clock 17 is divided into a plurality of compartments 41, along its length and width, each sealed from the others and each group of laterally disposed compartments being fitted with means for controlling the buoyancy of that group of compartments. The drydock may be provided with few or many compartments, as desired. As may be seen more clearly from FIG. 6 such buoyancy control means may include an air pump 43 and an air pressure tank 45 whereby compressed air is used to force water from the interior of the tanks through valves 47 below the normal waterline thereof. Obviously a water pumping system with valves could also be employed for controlling the amount of water in the tanks 41. The side tanks of the group of laterally disposed compartments or tanks 41 may be used to trim or right the ship transversely if the ship has a list to one side. The side tanks may be controlled from any suitable location, e.g. a separate pump house. The side tanks may be filled or drained in any suitable conventional manner with pumps and valves for preventing such list of the ship.

An automatic control system is provided for controlling the action of the pumps 43. As shown schematically on FIG. 6, this system includes a pump control unit 49 operated by a position sensing means shown generally at 51. The sensing means 51 comprise a float 53 which is tied to the pontoon dock 17 by means of a chain, flexible cable or the like 55. Mounted on the float 53 are a pair of fixed spaced electrical contact points 57, 59 which are connected to the pump control 49. A third contact point 61, positioned between points 57 and 59, is rigidly attached to the pontoon dock 17 and is also electrically connected to the pump control 49. In operation as the pontoon compartments sink lower in the water due to increased loading or raises due to decreased loading, the

point 61 makes electrical contact with either contact point 57 or contact point 59 thereby closing an electrical circuit to cause the pumps and their controls to either pump air into the compartments or tanks 41 forcing water out of valves 47 causing the pontoon to increase its buoyancy, or alternatively, release air from the tank thru suitable valve means thereby allowing the tank to flood and sink lower in the water. The valves may be spring biased or solenoid controlled for instant opening and closing. As soon as the pontoon compartments are raised or lowered sufficiently to break the electrical contact between point 61 and either of points 57 or 59, the control unit stops the pump action. Other electrical devices which are sensitive to the position of the pontoon relative to the water level may be used to activate the pump control unit 49. The sensing means shown generally at 51' in FIG. 7 may include a sensing unit 63, aflixed to the pontoon 17, which is sensitive to immersion in water.

FIG. 8 shows another possible configuration of an automatic pump control sensing means; in this case the sensing means being responsive to stress on the rails 19. A pressure sensitive transducer is positioned beneath one of the rails 19 and provides an electrical output, dependent on the loading of the rail, to actuate the pump control unit 49.

FIG. 9 illustrates a view in cross-section of the pontoon dock 17 showing relative water levels in the tanks 41 as the ship 33 is being transferred between the pontoon to the dockside railway 25. It will be realized that the system functions equally well during both drydocking and undocking operations, and that an existing floating dock altered and equipped with the present apparatus could serve as the turntable.

Thus there has beendescribed a drydocking system adaptable for repairing a large number of ships at a time or for building large equipment such as ships or rockets which are easily water transportable. The system described eliminates prior art problems in such systems while including many advantages not possible with prior art systems.

Obviously many modifications and variation of the present invention are possible in the light of the above teachings. For example, in shipyards with little rise and fall of the tide, the caisson could be omitted and an existing floating dock could be altered and equipped with the automated buoyancy control system disclosed herein, and the facility could serve as the turntable in lieu of building a new turntable. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A drydocking and undocking system comprising:

a drydock basin;

a pontoon dock adapted to fit within said drydock basin; a plurality of compartments in said pontoon dock;

means for selectively controlling the buoyancy of selected compartments of said pontoon in response to variations in loading on said pontoon compartments;

means for selectively controlling the buoyancy of the compartments of said pontoon dock including means for controlling the buoyancy of each of said compartments individually;

said means for controlling the buoyancy of each of said compartments including pump means, and means responsive to the water level of said pontoon at said compartment for controlling said pump means wherein the buoyancy or uplift of the pontoon is responsive to displacement of the said compartments of the pontoon under the loading on the pontoon and under variations in the loading.

2. Shipyard apparatus comprising in combination:

a drydock basin;

a pontoon dock within said basin, said pontoon dock 6 having suflicient length to substantially span said basin; said pontoon dock having transport means mounted thereon;

a plurality of compartments in said pontoon dock; and

buoyancy control means for selectively controlling the buoyancy of selected compartments of said pontoon in response to variations in loading on said pontoon compartments;

said buoyancy control means include pumping means and pump control means responsive to the loading on each compartment of said pontoon dock for controlling the operation of said pump means, wherein the buoyancy or uplift of the pontoon is responsive to displacement of the said compartments of the pontoon under the loading on the pontoon and under variations in the loading.

3. Shipyard apparatus as defined in claim 2 wherein said pump control means comprises means for detecting the level of the compartments portions of said pontoon dock with respect to the water. i

4. Shipyard apparatus as defined in claim 2 wherein said transport means includes a railway mounted on said pontoon dock and said pump control means comprises means for detecting the loading stress on the tracks of said railway on said pontoon dock at preselected points in relation to said compartment portions of the pontoon dock.

5. Shipyard apparatus as defined in claim 2 wherein said pumping means include an air pump for pumping air into said compartments of said pontoon dock.

6. Shipyard apparatus as claimed in claim 2 wherein lateral groups of said compartments are provided, and said control means comprises means associated with each lateral group of compartments for sensing the displacement of that compartment group relative to the exterior water level whereby the longitudinal loading distribution of a ship supported on said pontoon dock is compensated for by relative displacement of the groups of said compartments longitudinally of the pontoon dock.

7. Shipyard apparatus as defined in claim 3 wherein said level detecting means comprises a float which is flexibly attached to the pontoon dock, a pair of spaced electrical contact points carried-by said float, and an electrical contact point on the pontoon dock and positioned between the said pair of contact points on the said float, all of said electrical contact points being electrically connected to the said pump control means.

'8. Shipyard apparatus comprising in combination:

a fixed non-floating drydock basin;

said basin comprising a center portion and portions on either side of said center portion;

said side portions of said basin being of less depth than said center portion;

a pontoon dock of sufiicient length to span said center portion of said basin fitted within said basin and rotatable within said basin;

said center portion being sufiicient size to receive said pontoon dock;

said side portions of said basin being of suflicient depth to accommodate the pontoon dock when the same is floating with its upper surface near to the level of the top edges of the said basin, and with the end portions of said pontoon overlying said side portions of said basin, and its central portion over-lying and spanning the said center portion of the basin.

9. Shipyard apparatus as defined in claim 8, wherein said pontoon dock is provided with key means on its vertical walls, and the vertical walls of the said basin are provided with keyway means for receiving said key means on the pontoon for holding the pontoon against transverse movement after it is placed in a desired position.

10. A system for drydocking a ship upon the shore of a yard utilizing a turntable floating pontoon dock in an open ended basin defined by said shore of the yard, comprising:

su=bmerging in said basin the floating pontoon dock =by flooding water therein;

floating the ship over the submerged pontoon dock in said basin;

removing water from the pontoon dock causing it to raise the ship out of the water;

floating a caisson into the open end of said basin in a manner to seal Water within said basin;

raising the water level Within said basin sufficiently high to elevate the floating pontoon dock with the ship thereon to the level of the surface of the shore of the yard;

positioning the floating pontoon dock to align with a facility on said shore of the yard; and

transporting the ship from said pontoon dock onto said shore of the yard.

References Cited UNITED STATES PATENTS Turnbull 61-65 Watts 6165 Dutton 6165 Hohorst 6165 Wardle 114125 Hermanson 114121 X Piry 114 -121X Usab 114.5 Fieser 246-249 Mac-hol et al 6164 Collipp 114.5

FOREIGN PATENTS Germany. Great Britain.

DAVID J. WILLIAMOWSKY, Primary Examiner. JACOB SHAPIRO, Examiner. 

1. A DRYDOCKING AND UNDOCKING SYSTEM COMPRISING: A DRYDOCK BASIN; A PONTOON DOCK ADAPTED TO FIT WITHIN SAID DRYDOCK BASIN; A PLURALITY OF COMPARTMENTS IN SAID PONTOON DOCK; MEANS FOR SELECTIVELY CONTROLLING THE BUOYANCY OF SELECTED COMPARTMENTS OF SAID PONTOON IN RESPONSE TO VARIATIONS IN LOADING ON SAID PONTOON COMPARTMENTS; MEANS FOR SELECTIVELY CONTROLLING THE BUOYANCY OF THE COMPARTMENTS OF SAID PONTOON DOCK INCLUDING MEANS FOR CONTROLLING THE BUOYANCY OF EACH OF SAID COMPARTMENTS INDIVIDUALLY; SAID MEANS FOR CONTROLLING THE BUOYANCY OF EACH OF SAID COMPARTMENTS INCLUDING PUMP MEANS, AND MEANS RESPONSIVE TO THE WATER LEVEL OF SAID PONTOON AT SAID COMPARTMENT FOR CONTROLLING SAID PUMP MEANS WHEREIN THE BUOYANCY OR UPLIFT OF THE PONTOON IS RESPONSIVE TO DISPLACEMENT OF THE SAID COMPARTMENTS OF THE PONTOON UNDER THE LOADING ON THE PONTOON AND UNDER VARIATIONS IN THE LOADING. 